Asterisk realtime, mwi, and not using rtcachefriends=yes

I am using Asterisk realtime to access a MySQL database connected to OpenSER. The Asterisk box is acting solely as a voicemail system; the OpenSER proxy acts as registrar, too. A view in MySQL maps the OpenSER subscriber table to the Asterisk’s required tables for peers/friends and voicemail users. Voicemail is and has been working properly with this setup.

Apparently MWI does not work with Asterisk realtime unless using rtcachefriends=yes. However, with this configuration Asterisk must have its sip users reloaded each time a change is made to OpenSER’s database, such as deleting a user or changing a password. Is there currently any method of using MWI without this caching? Would a cron job be a feasible solution if there isn’t?

Also, to maintain simplicity and to allow the user to update their password by phone, I have mapped the view only to the subscriber table, and not to the location table. This means Asterisk does not know the IP:port of the SIP UA. Is it possible to have Asterisk forward all messages to my SIP proxy?